Separation Of Lanthanum Research Articles

A Pyridine Amine Extractant for Separation of La3+ and Ce3+ in HNO3 Solution.

The separation of lanthanum and cerium is of great significance for improving the material properties and promoting scientific and technological progress. In this paper, a pyridine amine extractant, (1R,2S)-N1,N2-bis((5-methylpyridin-2-yl)methyl)cyclohexane-1,2-biamine (cis-BMPyMChBA), was designed for the separation of lanthanum and cerium. The aim is to use this extractant to catalyze the oxidation of tri- to tetravalent cerium and to increase the separation efficiency between lanthanum and cerium. The effects of the temperature, diluent, extractant concentration, and pH were evaluated to the extraction and separation performance of lanthanum and cerium. The experimental results demonstrate that cis-BMPyMChBA exhibits high selectivity for cerium, with a separation factor for lanthanum and cerium reaching 122.9. The coordination mechanism between cis-BMPyMChBA and cerium ion was clarified through the combined use of extraction isotherm, Job's curve, spectroscopic methods, and density functional theory (DFT) calculation. It involved the interaction between the secondary amine N atom and the pyridine N atom and the metal ion in which the cerium ion underwent a valence change from trivalent to tetravalent before extraction. This was found to be more conducive to the separation of lanthanum and cerium.

Nanohydrometallurgy with superparamagnetic nanoparticles for selective separation of lanthanum from a real spent catalyst

Nanohydrometallurgy with superparamagnetic nanoparticles for selective separation of lanthanum from a real spent catalyst

Determination of optimum conditions for the extraction and separation of lanthanum, cerium, yttrium and thorium using Taguchi method

Determination of optimum conditions for the extraction and separation of lanthanum, cerium, yttrium and thorium using Taguchi method

Separation of lanthanum and neodymium in a hollow fiber supported liquid membrane: CFD modelling and experimental validation

Nickel metal hydride batteries find extensive use in many electronic devices. They contain a small amount of rare earth elements, such as, lanthanum and neodymium, which can be recovered from waste batteries, and reused. Hollow fiber supported liquid membranes (HFSLM) have been used for separation of different metal ions. In this work, a CFD model has been developed for a HFSLM to study the separation of lanthanum ion (La+3) and neodymium ion (Nd+3) from an aqueous solution. The model considers the effect of pH on distribution coefficient DM, which is a function of hydrogen ion (H+) concentration, and has a significant effect on extraction efficiency. The model was validated with the experimental data. An empirical model was fitted with the simulation data, and the parameters were optimized for the effective separation of La+3 and Nd+3. The maximum extraction of Nd+3 was predicted to be 44.97%, whereas extraction of La+3 was estimated to be 3.39%, at the optimized conditions of flow rate: 118.96 ml/min, feed pH: 3.41, and [PC88A]: 41.63 mol/m3, in once-through mode. The proposed CFD model could be helpful in design as well as, scale-up of HFSLM for separation of metal ions, by changing the design and process parameters.

Study of lanthanum-didymium separation by solvent extraction from a liquor conditioned with lactic acid

Rare earth elements (REE) have increased in importance in the world due to the diverse applications in high-tech industries. The fact that Brazil has the world’s second largest REE reserves makes it a potential producer of these elements. However, for that to occur, it is necessary to have knowledge about the production technologies of rare earths, mainly the technologies used in the refining stages, in which China predominates. Generally, the leached solution contains a mixture of REE and the main challenge is to improve selectivity during their separation and purification. For this reason, techniques to improve the efficiency of the separation of these elements have been widely studied in recent years. In the present study, we seek to define efficient routes for the separation of lanthanum (La) from didymium (Pr and Nd) by the solvent extraction technique (SX), using the organophosphorus extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) from a liquor conditioned with lactic acid. Isotherms were constructed using the McCabe-Thiele method to estimate the number of theoretical stages and the aqueous/organic ratio (A/O) necessary to achieve efficient separation during the process. In continuous solvent extraction experiments, REE recovery percentages and purity of didymium and lanthanum above 90% were obtained. Didymium with 99.9% purity was obtained in a circuit with nine extraction stages (extraction A/O ratio of 4:1) and seven scrubbing stages (scrubbing A/O ratio of 2:1). The results presented here show that the use of lactic acid can be a promising alternative to boost the efficiency of the solvent extraction process for the separation of these light rare earth elements.

Separation of Lanthanum(III) by Selective Precipitation from Sulfuric Acid Solution Containing Iron(III)

철(III)과 란타넘(III)이 혼합된 황산용액에서 황산나트륨에 의한 란타넘 복염의 침전 및 분리를 조사했다. 복염 침전에 영향을 줄 수 있는 여러 요인 중 황산나트륨 및 란타넘(III)의 농도, 반응온도 및 시간, 그리고 철(III) 농도에 대해 조사했다. 용액 중 Na+, SO42- 이온 및 란타넘(III) 농도가 높을수록 희토류 복염의 침전률이 증가했고, 반응온도가 100°C까지 증가함에 따라 란타넘 황산염 이온의 형성을 촉진해 희토류 복염의 침전률이 증가했다. 또한 반응시간이 증가할수록 철(III)의 침전률이 감소해 3시간 이후에는 거의 침전되지 않았고, 철(III) 농도는 복염 침전에 큰 영향을 미치지 않았다. 황산용액에 황산나트륨을 첨가하면 란타넘(III)을 선택적으로 침전시켜 철(III)과 분리할 수 있다.

Green separation of lanthanum, cerium and nickel from waste nickel metal hydride battery

In a circular economy context, there is a growing need for more sustainable waste management options to recover elements from end-of-life materials. These “secondary ores” represent a source of critical elements that are often present in higher concentration compared to their primary ore. In this work, the recovery of lanthanum (La) from waste nickel metal hydride battery (NiMH) leachate is investigated using an aqueous biphasic system (ABS) process based on a pluronic triblock copolymer (L35). An initial screening is performed to determine the influence of the ABS phase forming salt anion and alizarin red extractant on the La extraction efficiency and selectivity. From these results, a three-step ABS process is developed, varying only the nature of the salt and requiring no additional extractant. In a first step, the ABS composed of L35 + thiocyanate ammoniun + H2O efficiently extracts iron, manganese, and cobalt leaving La, cerium, and Ni in solution. Nickel is subsequently recovered by precipitation using dimethylglyoxime. Finally, La is separated from cerium using the L35 + ammonium nitrate + H2O ABS, recovering 62 g of La with 94% purity per kilogram of black mass of NiMH battery. This work highlights the applicability of ABS for the treatment of raw and complex matrices, potentially allowing for a greener hydrometallurgical treatment of wastes.

Adsorption of lanthanum and cerium on chelating ion exchange resins: kinetic and thermodynamic studies

ABSTRACT As the demand for rare earth elements (REE) increases in the coming years, techniques to obtain these elements from different sources may be explored. A hydrometallurgical route may achieve the sustainable approaches signed by countries. For this, separation techniques need to be explored, and chelating ion exchange resins are the most prominent. For this reason, to enhance the possibilities for REE separation, the main focus of this work was to study kinetics models and the thermodynamics of lanthanum and cerium adsorption at laboratory scale under industrially operating conditions. Three different functional groups were evaluated through the chelating resins M4195, TP207, and XUS43605. The effect of pH and resin dosage were evaluated, as well as the kinetic models (pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion) and thermodynamic parameters. The results presented here could be used for industrial applications. Pseudo-second order provided a better fit for both M4195 and TP207, and the intraparticle diffusion fitted better for XUS43605. Thermodynamic experiments have shown that the adsorption of lanthanum and cerium are spontaneous and endothermic. These findings represent the novelty of the present study since it could be used in selective separation of lanthanum and cerium onto chelating resins from primary and secondary sources.

Transport and kinetics properties of LaF3 in FLiNaK molten salt determined by electrochemical methods

It is found that lanthanum species can exist in the form of LaF63− in FLiNaK (46.5 LiF-11.5 NaF-42 KF, mol%) molten salt in previous studies. The understanding of transport and reaction kinetics parameters of LaF63− ions in FLiNaK molten salt is essential for the electrochemical separation of lanthanum from FLiNaK melt to achieve the coolant clean-up in fluoride salt cooled high-temperature reactor (FHR). Through conducting chronopotentiometry tests, the diffusion coefficients of LaF63− ions in FLiNaK molten salt at the temperature range of 923 K–1023 K were determined. By conducting potentiodynamic polarization measurements at different concentrations and temperatures, the exchange current density, reaction rate constant, and charge transfer coefficient were obtained. The experiment data of potentiodynamic polarization were analyzed using a non-simplified electrode kinetics equation which incorporates both mass transfer and reaction kinetics.

Study on the feasibility of using a pilot plant Scheibel extraction column for the extraction and separation of lanthanum and cerium from aqueous solution

Batch and continuous experiments were carried out in a Scheibel extraction column to separate La(III) from Ce(III). Central composite design was used to evaluate the influence of pH, extractant concentration in the batch experiments, and the influence of rotor speed, phase flow rates in the continuous experiments. At optimum conditions (pH 3.5, D2EHPA extractant concentration 0.05 M, rotor speed 128 rpm, dispersed phase flow rate 32 L/h and continuous phase flow rate 18 L/h), high extraction efficiency and separation factor equal to 88.12% and 4.89, respectively, for cerium separation from lanthanum were reasonably well predicted by the model. At higher rotor speed, La(III) and Ce(III) ions move faster from aqueous to the organic phase, which retards the higher interaction between ions and D2EHPA extractant. The results showed that this extraction column could be a potential candidate for the extraction and separation of La(III) and Ce(III) ions or other industrial wastewater.

Study of the separation of didymium from lanthanum using liquid-liquid extraction: Comparison between saponification of the extractant and use of lactic acid

The liquid-liquid extraction (LLE) technique is widely used for industrial-scale separation of rare-earth elements (REEs). However, the low selectivity of LLE in separating REEs, mainly adjacent elements, has prompted the investigation of modifications of this technique to find new routes that are more efficient. The selectivity of REEs separation increases when saponified extractants are used. However, saponification generates effluents containing sodium or ammonium ions that need to be removed before discharge into water bodies or be reused. As an alternative to saponification, the conditioning of the feed liquor with complexing agents has been proposed. This study compares the efficiency of didymium (Pr + Nd) and lanthanum separation with saponified and non-saponified organophosphorus extractants and with addition of lactic acid to the feed liquor. The extractants investigated were D2EHPA, P507 and Cyanex 272. The effect on the didymium/lanthanum separation of initial pH, saponification degree and lactic acid concentration and extractant were evaluated. The La and didymium separation were better when the feed solution was conditioned with lactic acid than when the extractants D2EHPA and P507 were saponified. Conversely, La and didymium separation was better when Cyanex 272 was saponified than when the feed liquor was conditioned with lactic acid. These results indicate that conditioning the feed liquor with lactic acid has the potential to replace the practice of saponification of the extractants D2EHPA and P507.

Simultaneous CO2 capture and metal purification from waste streams using triple-level dynamic combinatorial chemistry.

A reduction in CO2 emissions is required to mitigate global warming. Post-combustion carbon capture is one of the most developed technologies that has the potential to meet this goal, but its cost prevents its widespread use. A different approach would be to use CO2 directly as it is captured, before it is stored. Here we explore spontaneous CO2 fixation by industrial polyamines as a strategy to generate dynamic libraries of ligands for metal separation and recovery. We identify the CO2 loadings and solvents promoting the optimal precipitation of each metal from the dynamic libraries of complexes. We demonstrate the separation of lanthanum and nickel using the exhaust gas of an internal combustion engine vehicle, and show that the three metal constituents of the La2Ni9Co alloys used to manufacture the batteries of electric vehicles can be separated and recovered by successive CO2-induced selective precipitations. Beyond the concept of CO2-sourced multi-level dynamic coordination chemistry, this study provides a potential framework for integrated CO2 capture and use through sustainable processes.

Adsorption of La (III) on Chitosan-Imprinted Nano Zero-Valent Iron Nanocomposite (CS@nZVI): Process Optimization, Isotherm, Kinetic, and Thermodynamic Studies

Background: The recovery of rare-earth elements (REEs) like toxic lanthanides from contaminated waters is vital because of their irreversible effects on humans and the environment. Objectives: In the present research, a chitosan-imprinted nano zero-valent iron (CS@nZVI) nanocomposite was fabricated and utilized to the successful separation of Lanthanum as a model lanthanides. Methods: The morphological and structural properties of the composites were studied through BET, FTIR, SEM, TEM, and XRD techniques. The adsorption process was modeled and optimized by methodology of response surface (RSM). Then, its four important models were validated by data fitting. Afterward, they were affirmed using ANOVA test. Results: According to the outputs of the models, the reduced model was obtained as an appropriate model. Based on RSM plots, the adsorption rate at preliminary pH is low and gets better with increasing the pH value. At lower pH, there is a high concentration of H+ ion with smaller ionic radii and higher adsorption possibility, which makes it difficult to adsorb lanthanum ions by creating a competition between the excess of protons in the solution and cationic metal ions. This competitive adsorption and saturation of adsorptive sites on the surface of CS@nZVI sorbent with hydrogen ions together with repulsion forces are responsible for the La (III) less sorption. The optimum CS@nZVI removal efficiency of La (III) was 88% under the following conditions: pH = 8, 1.2 g/L CS@nZVI dosage, 5 mg/L initial La (III) concentration, and 180 min shaking time. Based on uptake kinetic models, the pseudo-second-order model is optimum in describing the rate equation of the adsorption process. Conclusions: Successfully regeneration of CS@nZVI along with its good performance for Lanthanum separation provide a promising and feasible method in order to contaminated streams purification.

Lanthanum and Cerium Separation Using an Aqueous Two-Phase System with Ionic Liquid

In this work, an organic solvent-free extraction approach was developed to selectively separate La from Ce using an ionic liquid-based aqueous two-phase system (ILATPS). ILATPSs composed of 1-ethyl-3-methylimidazolium chloride, C2MIMCl, K2CO3 (or K2HPO4), and water at 283, 298, and 313 K were obtained. The biphasic region decreased slightly with increasing temperature. These ILATPSs were applied for the separation of lanthanum from cerium. Some parameters that affect the separation of La and Ce, such as the alkyl chain length of the imidazolium cation, the type of electrolyte, and extractant concentration, were investigated. The best conditions for separation were achieved using the ILATPS formed by C2MIMCl + K2CO3 + H2O and 40.4 mmol kg–1 alizarin red S (as an extractant). The extraction percentage for La was 100%, whereas the extraction for Ce was 5.4%, yielding a separation factor between La and Ce equal to 2620.

Molybdenum and lanthanum as alternate burn-up monitors – development of chromatographic and mass spectrometric methods for determination of atom percent fission

Abstract A rapid high performance liquid chromatography (HPLC) and thermal ionisation mass spectrometric (TIMS) methods have been developed for the separation and estimation of fission product elements molybdenum and lanthanum for the burn-up measurements on the dissolver solution of Indian pressurised heavy water reactor (PHWR) spent fuel. Reverse phase chromatography method was developed to separate molybdenum from dissolver solution using mandelic acid as mobile phase and a dynamic ion exchange chromatography technique was used for the separation of lanthanum as well as neodymium from a dissolver solution. Sample loading methods which resulted in enhanced ionisation efficiency have been developed for the TIMS analysis of HPLC separated molybdenum and lanthanum fractions. Ascorbic acid mixed with silicic acid in HCl medium was used for loading the molybdenum on to a rhenium filament to obtain stable and intense ion beam. A novel sample loading method for lanthanum in which a mixture of graphite + boric acid (H3BO3) + silica gel was employed to achieve enhanced and steady ion beam formation of LaO+. Concentrations of species of interest were determined employing suitable spikes by isotope dilution mass spectrometry (IDMS) method. The developed methods were adopted for PHWR dissolver solution to establish molybdenum and lanthanum as alternate burn-up monitors. The burn-up data obtained were compared with the well established method of neodymium as fission product monitor. This is a first study of its kind where the data obtained by using molybdenum and lanthanum as fission product monitors were compared with that obtained by Nd-148 method.

Electrochemical Investigation of Molten Lanthanum-Yttrium Oxide for Selective Liquid Rare-Earth Metal Extraction

The electrochemical separation of lanthanum from yttrium as liquid metal is investigated starting from their molten mixture as sesquioxides, La2O3 and Y2O3, at temperature in excess of 2500K. Using iridium electrodes, a combination of dc and ac electrochemical methods and a thermal imaging furnace, the selectivity for liquid rare-earth metal recovery is evaluated for 6 compositions across the pseudo-binary La2O3 - Y2O3. Departure from the thermodynamic predictions based on ideal mixture for the molten rare-earth oxides and their alloy is experimentally demonstrated, with selectivity several order of magnitude different than the standard state predictions. A critical assessment of a possible model for the thermodynamic of mixing is presented to describe the non-ideal mixing behavior for the pseudo-binary La2O3 - Y2O3. The selective enrichment observed using molten rare-earth electrolysis suggests a possible new approach for direct, selective, REE separation and recovery.

Extraction of Lanthanide Nitrates in Multicomponent Aqueous-Organic Two-Phase Systems with D2EHPA

Lanthanum nitrate distribution in three-component aqueous-organic systems with D2EHPA from acetate or acetic acid–acetate solutions has been studied, it has been shown that variation in sodium acetate concentration or composition of CH3COONa–CH3COOH mixture can affect metal distribution ratios. It has been found that extraction in three-component mixture of 1: 1: 1 composition (aqueous solution Ln(NO3)3 + CH3COONa + CH3COOH–D2EHPA in hexane–isopropyl alcohol) can provide lanthanide separation, which is dependent on the ratio of sodium acetate and acetic acid in aqueous phase and on D2EHPA concentration in organic phase. Lanthanide–lanthanum separation factors have been calculated for the extraction of lanthanide nitrates from acetic acid–acetate solutions.

Extraction and separation of La(III), Pr(III) and Nd(III) using binary mixture of D2EHPA with Cyanex272, TOPO, and TBP extractants

This paper investigated the extraction and separation of lanthanum(III), praseodymium(III) and neodymium(III) from aqueous hydrochloric acid solutions using a mixture of di-(2-ethylhexyl) phosphoric acid (D2EHPA) with three other extractants, namely bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272), trioctylphosphine oxide (TOPO) and tri butyl phosphate (TBP) diluted in kerosene. In this study, the O/A = 1, T = 25 °C (room temperature), contact time of 10 minutes for the two phases, and kerosene as the diluent were chosen for all experiments. The effective factors studied in this research included the type and concentration of extractants as well as the pH of solutions. The Design Expert software was employed for the design of experiments, investigating the factors effect on the solvent extraction and the separation factor (β), and obtaining the optimal values of the factors. After a thorough analysis of the experiments, it was concluded that these factors were independent and had no interaction on each other. The maximum extraction and separation of Pr(III) and Nd(III) were attained by the mixture of D2EHPA and Cyanex272 in which the ratio of D2EHPA to Cyanex272 equaled 0.5 at pH = 4.4. Their extraction values were 90.5%, 91.3% respectively and β(Nd+Pr)/La = 14.4. In this condition, the extraction of La(III) was 50.81%. Based on this data, a two-stage extraction was used for the separation of Nd and Pr from the La, with an extraction efficiency of 97.5%, 96.9%, and 28.3% for Nd, Pr, and La, respectively. In order to selectively remove the co-extracted La from the loaded organic phase (D2EHPA + Cyanex272), the scrubbing of La was carried out with a new immiscible aqueous solution of Nd with the concentration of 251 mg/L as the scrubbing solution with a scrubbing efficiency of 85%.

Separation of lanthanum and cerium from chloride medium in presence of complexing agent along with EHEHPA (P507) in a serpentine microreactor

The effect of operating parameters on the extraction and separation of La and Ce, from chloride solution containing one complexing agent lactic acid, using 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA, P507) as an extractant, has been studied. Results show that extraction efficiencies increase as pH and residence time increase, while decrease with the increasing of channel width and mixture velocity. A better separation effect is obtained using microfluidic extraction at optimal conditions. The extraction rates (0.1214 s−1 for La and 0.3231 s−1 for Ce) determined in microfluidic extraction, are much larger than those (0.0058 s−1 for La and 0.0068 s−1 for Ce) in conventional solvent extractors, which are largely attributed to the higher surface-to-volume ratio achieved in microfluidic experiments. The overall mass transfer coefficients (KLa) increase with increase in mixture velocity, while decrease with increase in channel size including channel width and length. The significant difference in KLa of Ce (0.05–0.162 s−1) as compared to La (0.004–0.129 s−1) imply better separation effect. Compared with conventional extractors such as mixer-settler and centrifugal extractor, microfluidic extraction has much higher mass transfer rates.

The Influence of Lactic Acid Concentration on the Separation of Light Rare Earth Elements by Continuous Liquid–Liquid Extraction with 2-Ethylhexyl Phosphonic Acid Mono-2-ethylhexyl Ester

The separation of rare earth elements (REEs) using solvent extraction adding complexing agents appears to be an alternative to saponification of the extractant. We evaluated the effect of lactic acid concentration on didymium (praseodymium and neodymium) and lanthanum extraction with 2-ethylhexyl phosphonic acid mono-2-ethyl hexyl ester [HEH(EHP)] as extractant. First, we investigated in batch experiments the separation of lanthanum (La) and didymium (Pr and Nd) using McCabe–Thiele diagrams to estimate the number of extraction stages when the feed solution was or was not conditioned with lactic acid. Additionally, we conducted continuous liquid–liquid extraction experiments and evaluated the influence of lactic acid concentration on the REE extraction and separation. The tests showed that the extraction percentage of REEs and the separation factor Pr/La increased when the lactic acid concentration increased, but the didymium purity decreased. Lanthanum, praseodymium, and neodymium extraction rate were 23.0, 89.7, and 99.2 pct, respectively, with 1:1 aqueous/organic volume flow rate and feed solution doped with 0.52 mol L−1 lactic acid. The highest didymium purity reached was 92.0 pct with 0.26 mol L−1 lactic acid concentration.